Field of the Invention
The present invention relates to an image processing apparatus such as a multi-function peripheral (MFP), i.e., a multifunctional digital image forming apparatus, and an image processing method for the image processing apparatus.
Description of the Related Art
The following description sets forth the inventor's knowledge of related art and problems therein and should not be construed as an admission of knowledge in the prior art.
Image processing apparatuses are commonly provided with a high-speed scanner. Once a high-speed scanner starts taking images from a document to input image data to the image processing apparatus it cannot stop until it finishes the entire document. With this scanner, a memory area equivalent to one page of raw data or compressed encoded data needs to be reserved.
There are the following types of memory for image processing apparatuses: a main memory that allows free accesses from a CPU and can be expanded as needed; a sub memory that allows only direct memory accesses (DMA) and has as much memory area only as the device configuration requires; and a backup storage device for storing a great size of encoded data.
Main memory is more expensive than sub memory because it is expandable as needed. In order to reserve a band wide enough for image transfer, a main memory and a sub memory need to be installed in such a manner that they can be accessed through different channels.
After a memory area equivalent to one page of image data is reserved in the main memory, the image processing apparatus achieves fast image inputs with an automatic document feeder attached to the scanner. In order to achieve the best speed performance, the number of pages of image data that can be stored at a time can be controlled by configuring the automatic document feeder, however, it is very common to do the same by expanding memory.
For example, there are image processing apparatuses provided with a dual scan-enabled automatic document feeder and some of them are allowed to store four A3 sized pages of image data at a time in their main memories. There are other image processing apparatuses provided with a normal automatic document feeder and most of them are allowed to store two A3 sized pages of image data at a time in their main memories.
Meanwhile, image processing apparatuses normally have at least one standard function to be available upon start-up of the image processing apparatuses themselves. The image processing apparatuses may further have at least one optional function to be available by settings upon user request.
The standard function will be available by a CPU starting a program for the standard function and the optional function will be available by a CPU starting a program for the optional function. Upon the optional function being available, the CPU requires more memory to execute a program for the optional function.
Conventionally, this problem is solved by expanding memory with extra memory for the optional function.
Meanwhile, Japanese Unexamined Patent Publication No. 2002-132520 suggests an apparatus that allocates memory on the basis of the availability of an optional function. The apparatus is configured to determine a memory map such that enough memory area can be later allocated to the optional function. On the basis of the technique disclosed in Japanese Unexamined Patent Publication No. 2002432520, the image processing apparatus can be configured to reserve a memory area for an optional function in the main memory when the optional function is installed.
The solution of expanding memory with extra memory for the optional function, however, brings a cost problem.
The solution of reserving a memory area for the optional function in the main memory does not contribute to effective use of the main memory, negatively affecting the speed performance. That is because, although all installed optional functions are not always used, memory areas for all the installed optional functions are reserved uselessly in the main memory and the reserved memory areas cannot be used for image input.
The description herein of advantages and disadvantages of various features, embodiments, methods, and apparatus disclosed in other publications is in no way intended to limit the present invention. Indeed, certain features of the invention may be capable of overcoming certain disadvantages, while still retaining some or all of the features, embodiments, methods, and apparatus disclosed therein.